Examples of an automatic transmission mounted on a vehicle include a gear-type automatic transmission constituted of a hydraulic coupling such as a torque converter and a gear transmission mechanism and a continuously variable automatic transmission constituted of two pulleys having an effective diameter variable depending on a hydraulic pressure and a metal belt wound on the pulleys.
The gear-type automatic transmission is connected to an engine via a hydraulic coupling such as a torque converter. The gear-type automatic transmission is constituted of a transmission mechanism (gear transmission mechanism) including a plurality of powertrains. For example, the gear-type automatic transmission is structured such that the powertrain is automatically shifted based on a degree of accelerator pressing down and a vehicle speed, that is, a speed change ratio is automatically shifted (gear combination is changed). In the gear-type automatic transmission, a gear is determined by engagement and disengagement of a friction element such as a clutch element, a brake element and a one-way clutch element into/from a prescribed state.
The continuously variable automatic transmission is also connected to an engine via a hydraulic coupling such as a torque converter. A belt-type continuously variable transmission, for example, achieves continuously variable shift by using a metal belt and a pair of pulleys and varying the effective diameter of the pulleys depending on the hydraulic pressure. More specifically, an endless metal belt is wound on a pulley on the input side attached to an input shaft and a pulley on the output side attached to an output shaft for use. Each of the pulley on the input side and the pulley on the output side is provided with a pair of sheaves of which recess width is variable in a continuous manner. By varying the recess width, a winding radius of each of the pulley on the input side and the pulley on the output side of the endless metal belt is varied, so that a ratio of rpm of the input shaft to the output shaft, that is, a speed change ratio, can be varied in a continuously variable manner.
In an automatic transmission of any type as described above, in general, a slide-type shift lever manipulated by a driver is provided in a vehicle equipped with an automatic transmission. Shift positions (such as a rearward drive position, a neutral position, and a forward drive position) are set based on a sliding manipulation of the shift lever.
Recently, in addition to a shift device implemented by such a slide-type shift lever, a shift-by-wire type shift device is also known. In the shift device of this type, shift manipulation by the driver is detected by a sensor or a switch (sensor kinds), and one position out of a plurality of positions is selected in accordance with a detection signal. In addition, in the shift-by-wire type shift device, the shift lever is not limited to a slide-type, and adoption of a joy-stick type manipulation member or a push-button type manipulation member is also proposed. As to the joy-stick type manipulation member, the driver tilts the lever in a forward/rearward and right/left direction so as to perform shift manipulation. When the lever is not manipulated, it automatically returns to a home position in the center by a biasing force of a spring, for example. Therefore, if the driver takes his hand off the lever after manipulation, the lever returns to the home position in the center, and it is no longer possible to check a current manipulation state from appearance.
When a push-button type manipulation member is adopted, the manipulation member (push button) state may automatically return to a pre-manipulation state after the driver finishes manipulation, and again it is impossible to check a current manipulation state from the appearance. Not only in these examples but also in a manipulation member of other types such as a touch-screen type manipulation member that automatically returns to its pre-manipulation state after manipulation by the driver (hereinafter, referred to as “momentary-type manipulation member”), it is sometimes impossible to check a manipulation state from appearance of a shift manipulation portion. Therefore, if such a momentary-type manipulation member is adopted in the shift manipulation portion, combined with discrepancy between a position shift procedure and a manipulation procedure, the driver may have uncomfortable feeling.
Japanese Patent Laying-Open No. 2002-264684 discloses a shift device of a vehicle capable of avoiding uncomfortable feeling of a driver due to adoption of a shift-by-wire type shift device. The shift device includes a gear range shifting mechanism, which is actuated to mechanically shift the actual gear ranges of a transmission; an actuator for actuating the gear range shifting mechanism; a manipulation range detecting circuit for detecting a manipulation range representing manipulation of a shift manipulation portion by a driver; an actual gear range detecting circuit detecting the actual gear range of the gear range shifting mechanism; and a controller for shifting the actual gear ranges of the transmission by controlling the actuator in accordance with detection signals from the manipulation range detecting circuit and the actual gear range detecting circuit. The shift device of a vehicle further includes a manipulation range indicating portion for indicating the manipulation range by the driver based on the detection signal from the manipulation range detecting circuit. The manipulation range indicating portion allows to indicate that the manipulation range does not correspond to the detection signal from the manipulation range detecting circuit.
According to the shift device disclosed in Japanese Patent Laying-Open No. 2002-264684, when the driver manipulates the shift manipulation portion, the actuator is driven in accordance with the manipulation range obtained based on the detection signals from the manipulation range detecting circuit and the actual gear range detecting circuit and the actual gear range of the gear range shifting mechanism, and gear range of the transmission is shifted by actuation of the gear range shifting mechanism. In addition, the manipulation range of the shift manipulation portion obtained based on the detection signal from the manipulation range detecting circuit is indicated by the manipulation range indicating portion. By providing the manipulation range indicating portion, it is ensured that the driver can recognize the manipulation range that he made. In particular, when the “momentary-type” manipulation member with which it is difficult to determine the manipulation range from the appearance is adopted in the shift manipulation portion, it will be difficult to have the driver accurately recognize the manipulation range without such a manipulation range indicating portion. In such a structure, a position setting of the transmission (actual position) is not necessarily shifted in synchronization with manipulation of the shift manipulation portion by the driver (manipulation position). According to this shift device, the manipulation range indicating portion allows to indicate that the manipulation range does not correspond to the detection signal from the manipulation range detecting circuit, and indication of the manipulation range can be set as required in a flexible manner without being bound by shift manipulation by the driver. Therefore, the shift device can be configured so as to avoid or mitigate uncomfortable feeling of the driver by modifying indication on the manipulation range indicating portion in a flexible manner if there may be a possibility to cause such feeling to the driver by maintaining indication as it is while usually having him/her accurately recognize the manipulation range.
On the other hand, the shift device disclosed in Japanese Patent Laying-Open No. 2002-264684 has the following disadvantage. The detecting circuit detects shift manipulation by the driver through the momentary-type manipulation member. Here, when a time for determining whether or not the momentary-type manipulation member is located at that position is uniquely set, a shift position different from that requested by the driver may be determined, depending on an environment (such as an ambient temperature of the shift device, a vehicle speed, a position requested by the driver, a state of power transmission by a powertrain, and the like) when shift manipulation is made through the momentary-type manipulation member. If determination is made in such a manner, the powertrain mechanism is controlled in accordance with that determination, resulting in a state not intended by the driver.